The present invention relates to an upper vehicle-body structure of a vehicle comprising a pair of right-and-left roof rails extending in a vehicle longitudinal direction at right-and-left both end portions of a roof portion of a vehicle body, a roof panel provided between the pair of right-and-left roof rails, a front header provided at a front portion of the roof panel in a vehicle width direction, a pair of right-and-left front pillars joined to the roof rails at upper portions thereof and extending downward, and a pair of right-and-left center pillars provided in back of the front pillars, joined to the roof rails at upper portions thereof, and extending downward.
An upper vehicle-body structure of a vehicle comprising a roof panel which forms a roof portion of a vehicle body and a roof reinforcement which is provided below the roof panel to extend in the vehicle width direction is known as exemplified by the upper vehicle-body structures disclosed in Japanese Patent Laid-Open Publication Nos. 2014-58224 and 2002-248943.
The above-described first patent document discloses the upper vehicle-body structure of the vehicle, in which the roof reinforcement is formed in a W shape in the side view such that it has joint faces to be joined to a lower face of the roof panel at its longitudinal-both end portions and its longitudinal-central portion and the other portion of the roof reinforcement than the above-described joint faces is spaced downward apart from the lower face of the roof panel, and this roof reinforcement is joined to the lower face of the roof panel. The structure of the above-described first patent document improves a tensional rigidity of the roof panel (see paragraphs [0038], [0049] of the above-described first patent document).
The above-described second patent document discloses a sunroof structure for a vehicle as the upper vehicle-body structure of the vehicle, in which first and second cross members as the roof reinforcement are arranged in an X shape in the plan view. The X-shaped first and second cross members increase a rigidity of the roof (see paragraph [0027] of the above-described second patent document).
However, the upper vehicle-body structures of the vehicle of the above-described first and second patent documents have been proposed aiming at improving a surface rigidity of the roof itself, not aiming at improving a torsional rigidity of a whole part of the vehicle body. Thus, further work for improvement of the torsional rigidity of the vehicle body has been needed.